Postman Settings

To interact with the built blockchain.py API over a network via the Postman App:

  • Select Authorization Type “No Auth” !
  • select “raw”
  • select “JSON” instead of “Text”

Set up python environment

# create a python environment
python3 -m venv env

# activate the python environment
source env/bin/activate

# install necessary packages in this environment
# Note: try newer version of Flask (I used version 2.0.2), if something does not work in the following)
pip install Flask==0.12.2 requests==2.18.4

Modify old blockchain.py

  • add the following app.config line:
# Instantiate the Node
app = Flask(__name__)
app.config['JSONIFY_PRETTYPRINT_REGULAR'] = False

Start the server

python3 blockchain.py -p 5001

http requests

General structure

Examples

  • GET http://localhost:5000/chain
  • POST http://localhost:5001/transactions/new

Examples

command description
GET /chain zeigt die gesamte Blockchain
GET /mine erzeugt einen neuen Block
POST /transactions/new fügt eine Transaktion zum nächsten Block (der noch nicht in der GET /chain Liste ist) hinzu, der geminet wird. Der nächste GET /mine Call erzeugt dann den Block, in dem diese transaction ist. Beispieltransaktion: 
{
    "sender": "d4ee26eee15148ee92c6cd394edd974e",
    "recipient": "someone-other-address",
    "amount": 5
}

Spin up another node on machine, on a different port [port 5001], and register it with current node [on port 5000]:

command description
POST nodes/register   
{
    "nodes": ["http://127.0.0.1:5001/"]
}

oder alternativ:

{
    "nodes": ["http://192.168.2.126:5001/"]
}
command description
GET /nodes/resolve replace shorter chains with the longest chain by the Consensus Algorithm